Sen. Rand Paul filibustered over the hypothetical drone targeting of American civilians on US soil. But critics say hundreds of other civilians already are being killed in US drone attacks in Pakistan and elsewhere.

People walk on the wreckage of a house destroyed by an air strike last year that was targeting al Qaeda-linked militants, in the southern Yemeni town of Jaar. U.S. drones have launched almost daily raids on suspected al Qaeda militants in Yemen, and air strikes have aggravated discontent among Yemenis, who say the strikes pose a threat to civilians.

Senator Rand Paul dominated the news this week with his 13-hour filibuster about the potential for armed drone aircraft dropping their deadly payloads on Americans here in the United States.

It was a hypothetical scenario designed to pressure the Obama administration into acknowledging that noncombatant US civilians – however much they might be suspected terrorists – would not be targeted while walking down the street or sitting in a café, that the president does not have the constitutional authority to do that.

Not so hypothetical is the issue of hundreds of other noncombatant civilians – women, children, and old men, mainly in Pakistan – ending up as collateral damage in US drone attacks aimed at those believed to be terrorists connected with Al Qaeda.

“We only authorize a strike if we have a high degree of confidence that innocent civilians will not be injured or killed, except in the rarest of circumstances,” Mr. Brennan said in a speech at the Wilson Center last April (at which time he was the Obama administration’s top counterterrorism official). “It is hard to imagine a tool that can better minimize the risk to civilians than remotely piloted aircraft.”

Under the circumstances, that’s difficult to prove. And as Natasha Lennard points out in Salon, “the very question of how the administration categorizes ‘civilian’ or ‘enemy combatant’ is in itself contentious.” It has been reported that the US government counts all adult males killed by strikes as “militants,” absent evidence which later shows them to have been innocent bystanders.

But that low-number assertion by Sen. Feinstein, Mr. Brennan, and others has been challenged by independent reports indicating much larger numbers of civilian casualties due to “targeted killings” by drones.

In their report titled “Living under Drones,” researchers at NYU School of Law and Stanford University Law School found “evidence of the damaging and counterproductive effects of current US drone strike policies” including “significant evidence that US drone strikes have injured and killed civilians.”

Drawing on the work of the London-based Bureau of Investigative Journalism, the NYU/Stanford researchers report that from June 2004 through mid-September 2012, drone strikes killed 2,562-3,325 people in Pakistan, of whom 474-881 were civilians, including 176 children, while injuring an additional 1,228-1,362 people.

“Drones hover twenty-four hours a day over communities in northwest Pakistan, striking homes, vehicles, and public spaces without warning. Their presence terrorizes men, women, and children, giving rise to anxiety and psychological trauma among civilian communities…. The US practice of striking one area multiple times, and evidence that it has killed rescuers, makes both community members and humanitarian workers afraid or unwilling to assist injured victims.”

“Some community members shy away from gathering in groups, including important tribal dispute-resolution bodies, out of fear that they may attract the attention of drone operators. Some parents choose to keep their children home, and children injured or traumatized by strikes have dropped out of school.”

"One of the questions we will be looking at is whether, given the local demography, aerial attacks carry too high a risk of a disproportionate number of civilian casualties," Ben Emmerson, the U.N. rapporteur on counterterrorism and human rights, told the British newspaper The Guardian.

While acknowledging the difficulty of gathering more precise data on civilian casualties caused by drones, the NYU/Stanford study says, "A significant rethinking of current US targeted killing and drone strike policies is long overdue…. US policy-makers, and the American public, cannot continue to ignore evidence of the civilian harm and counter-productive impacts of US targeted killings and drone strikes in Pakistan."

On Friday, Senators Rand Paul (R) of Kentucky and Ted Cruz (R) of Texas proposed a bill that would prevent the use of unarmed drones to attack American citizens on US soil. No mention of civilian casualties – perhaps hundreds of them – caused by US drone strikes in Pakistan and elsewhere.